A fast, private password strength checker
When you set up a new account or update your credentials, you naturally wonder: how secure is my password? This password strength checker gives you an instant, comprehensive analysis of your password's resilience against modern hacking techniques. As you type, the tool evaluates the complexity, length, and predictability of your input to provide a realistic security assessment.
Because security is paramount, this password checker runs entirely locally in your web browser. Nothing you type is ever uploaded, transmitted, or stored on any server. You can safely test password strength for your real accounts, knowing the data never leaves your device.
What the password checker measures
To give you an accurate picture of your security, the tool breaks down your password into several key metrics:
Overall Score: A quick visual indicator ranging from Very Weak to Very Strong. This score aggregates all the underlying data to give you a simple, actionable rating.
Password Entropy: Acting as a password entropy calculator, the tool measures the mathematical unpredictability of your password in "bits". Every additional bit of entropy doubles the number of guesses an attacker would need to make. A password with 30 bits of entropy is weak, while one with 80 bits or more is considered extremely secure.
Online vs. Offline Cracking Time: The tool estimates how long it would take an attacker to brute-force your password in two different scenarios. Online attacks happen against live login forms, which usually slow down attackers with rate limits and lockouts. Offline attacks happen when a hacker steals a database of hashed passwords and uses powerful graphics cards (GPUs) to guess billions of combinations per second. A password that takes centuries to crack online might only take seconds to crack offline if it isn't complex enough.
Vulnerability Feedback: If your password has structural weaknesses, the tool will point them out. It detects common dictionary words, sequential characters (like "1234" or "abcd"), repeated patterns, recent years, and a lack of character variety (such as missing uppercase letters or symbols).
Understanding password entropy
Entropy is the core concept behind password security. It is a mathematical measure of how many possible combinations an attacker has to guess to find your specific password.
Many people try to create strong passwords by taking a common word and adding a number and a symbol at the end (for example, Monkey1!). While this satisfies many basic password requirements, its entropy is actually quite low. Hackers know this trick, and their cracking software is programmed to try dictionary words followed by common numbers and symbols.
To achieve high entropy, you need a larger "search space." You can increase the search space in two ways: by adding different types of characters (uppercase, lowercase, numbers, symbols), or by making the password longer. Mathematically, increasing the length of your password adds far more entropy than simply adding a symbol to a short password.
Tips for creating uncrackable passwords
Use a passphrase. Instead of trying to remember a random string of characters like xK9#mP2@, string together four or five random, unrelated words (e.g., purple-coffee-balloon-stapler). Passphrases are much longer, which gives them massive entropy, but they are significantly easier for humans to remember and type.
Avoid predictable substitutions. Replacing the letter "a" with "@" or "e" with "3" (known as leetspeak) does not fool modern password cracking software. Attackers already have these substitutions built into their dictionaries.
Never reuse passwords. Even if you create a password with a Very Strong rating, it becomes useless if you use it across multiple websites. If one of those websites is breached, hackers will try your strong password on your email, banking, and social media accounts. Always use unique passwords for every service.
Use a password manager. The best way to ensure every account has a strong, unique password is to use a password manager. You only have to remember one highly secure master password, and the software handles the rest. If you need to create a new, highly secure string of characters, you can use our Password Generator to instantly create one. If you are setting up a new account and need a unique handle, try the Username Generator.